MRA Hyd ydrogeologists Analys ysis of E of EA R A Repor orts on - - PowerPoint PPT Presentation

MRA Hyd ydrogeologist’s Analys ysis

• f E
• f EA R

A Repor

• rts on
• n W

Water

MR MRA INTRODUCTION

Tim Lotimer is a professional geoscientist with 40 years’ experience, primarily with regard to municipal groundwater supplies. Some of his recent Class EA water supply projects were for the Regions of Halton and Waterloo, the Municipality of Chatham-Kent and the County of Brant. He is also on the Earth Sciences faculty at McMaster University. In 2016, the MRA retained Tim as an independent expert to analyse the water-related reports prepared by the developers’ consultants for the required MSP Environmental Assessment. Tim reviewed all relevant reports on the Township website. One key report is the Draft hydrogeological study report prepared by Golder Associates in June 2016 on the Midhurst Water Supply Exploration Program. Note that the final report has yet to be released, but is expected to remain essentially unchanged. In addition, Tim reviewed other publicly available reports which provide information on the Midhurst area; its geology, hydrogeology, existing water-takings and ecological characteristics. The following is the presentation he gave to Springwater Council on March 8, 2017. It is crafted from the viewpoint of the MRA’s concerns about the impact of the proposed water-taking on water users, wetlands and streams.

2

2017-03-08 3

CONCERNS

Impact on water users Water Quality Issues Impact on groundwater capacity Impact on fish & other wildlife Reliability of tools used to predict impacts Impact of sewage disposal Impact on wetlands/ streams

Additional 24,600 people Eleven new wells average demand : 9,825 m3/day maximum demand : 19,100 m3/day

B&V, May 2016

2017-03-08 4

Existing Wells New Wells

5

People and flow rates from B&V, May 2016 BLUE stars = existing wells– approximate location Red stars = proposed new wells – approximate location. Some locations have multiple wells (i.e. Snow Valley will have 3 wells) The water source will be 11 new wells. Sewage will be treated and discharged into Willow Creek.

Municipal Class EA

Phase 4: Selection of the preferred design

Must include a detailed discussion of: ➢ Identification of the potential impacts on the environment ➢ Description of mitigation measures to minimize environmental effects

2017-03-08 6

7 2017-03-08

Non-pumping level Pumping level Drawdown

How wells work

8

Many current residents of Springwater Township rely on wells for their private water supply. When a well is pumped the pumping level in the well drops. This is called drawdown. Not only is there drawdown in the well, but also drawdown in the aquifer. This is called the zone-of-influence of pumping.

2017-03-08 9

Impacts to Private Water Supply Wells

10

The above figure shows contour lines of the drawdown that results from pumping from the deep aquifer at 3 of the 4 proposed sites. As illustrated by the slide on the left, the drawdown is greatest near the wells and decreases as you go farther away. The purple colour is the zone-of-influence - the area where more than a metre of drawdown can be expected. It results from the pumping of these wells.

2017-03-08 11

Impacts to Private Water Supply Wells

• Well locations according to

Provincial database*.

• Only about 50% of the

existing wells are known to be included in the Provincial database*. * Text added by MRA

12

On the above slide, blue dots have been added to show the location of private wells in the MOECC water well record database. To assess impacts to these wells, it would be necessary to measure the normal pumping level in each of the wells and compare this to the predicted interference from pumping of the new wells. A complete door-to-door survey of private wells and their operating characteristics to allow this assessment cannot be found in the Golder (2016) report.

Impacts to Private Water Supply Wells

2017-03-08 13

• Enlarged view of Russell Rd showing only one well*.
• In reality, there are several more wells*.

* Text added by MRA

14

The MOECC water well record data base is not complete: wells are often missing. In the above slide, an area is shown where there are several homes but only one well is identified. Tim’s review of this specific MOECC database shows that there are wells within both the deep and shallower aquifers, which are contained inside the zone-of-influence of pumping. The aquifer testing program shows that, in some areas, pumping from the deep aquifer also causes drawdown in the shallower aquifers.

2017-03-08 15

Impacts to Land Owners

• Chart showing Well Head

Protection Areas where pollution is strictly controlled*

• Wells are located

at the darker end of shaded areas* * Text added by MRA

16

The colourful shapes on the above slide denote the Well Head Protection Areas (WHPAs) for the existing Midhurst and Snow Valley wells PLUS Barrie‘s municipal wells - all located within the Willow Creek subwatershed. The WHPAs provide an indication of the capture zone of the wells – where the water is coming from within the groundwater flow system. They also show the areas where limitations may be placed on property use according to the the Source Water Protection Plan. There are many farms and private rural dwellings within Springwater Township and adjacent Oro-Medonte Township which may be affected by these limitations. It is also important to note that some of the new wells will capture water that currently flows to the existing Midhurst municipal wells causing impacts on them. (Note that Barrie‘s water system uses wells drawing on aquifers which also supply Midhurst’s water for the north end and Lake Simcoe for the south end. The systems do not mix water; therefore, the wells shown here will continue to provide water for north Barrie.) Sources: Golder (2016) Study and the source protection MOECC Approved Assessment Reports for the City of Barrie and the Midhurst municipal drinking water systems.

Impacts of the Water Taking

• Current and proposed average daily and maximum daily demand of municipal

takings within the Willow Creek subwatershed

2017-03-08 17

Average Day Maximum Day Existing Midhurst Wells 1,450 m3/day 4,095 m3/day Existing Barrie Wells* 20,966 m3/day? 20,966 m3/day? Proposed New Wells 9,825 m3/day 19,014 m3/day TOTAL 32,241 m3/day 44,075 m3/day

* Operating capacity of wells within the Willow Creek subwatershed

18

When considering water impacts, the cumulative taking of all of the municipal water Supplies within the Willow Creek Sub-watershed must be included. The average daily taking from the proposed new wells is 1/3 of the total average daily municipal taking within the subwatershed. Sources: Barrie total taking in 2010 (groundwater base case) was 40,280 m3/day (Tier 3 Study). Of that amount, 17,800 m3/day is modelled groundwater inflow from the Willow Creek subwatershed. Midhurst takings from the SWP Assessment Report based on 2014 data. Proposed taking from B&V 2016. T3 Figure 1.2 shows Barrie Wells 9, 13 and 16 within the NVCA Willow Creek Subwatershed. T3 Table 3.1 shows PTTW Well 9 - 6,552 m3/day; Well 13 - 6,552 m3/day; Well 16- 7,862 m3/day

19 2017-03-08 19

Groundwater Flow

Impact of Proposed New Water Supply

• The water-taking from the municipal wells within the watershed is considered to

be consumptive taking ➢ A consumptive groundwater-taking occurs when the water is pumped from an aquifer, but not returned to the aquifer from which it was taken

• This results in a reduction of groundwater flow to the existing receptors

connected to the pumped aquifer (other groundwater users, streams and wetlands) that approximately equals the amount of water pumped

2017-03-08 20

21

Groundwater flow is from areas of recharge (typically the higher ground, such as the Oro Moraine) to areas of discharge (typically streams and wetlands). Groundwater moves through the pore spaces in the geological materials found below the surface. The movement is governed by gravity, with groundwater moving from areas of higher hydraulic potential to those of lower hydraulic potential.

Wetland Impacts

2017-03-08 22 Map from NVCA, 2015 - Minesing Wetlands

Cold groundwater from aquifers entering creeks and wetlands

23

The above slide on the left is from the NVCA. It shows the area of the Minesing Wetlands which is very dependent on groundwater discharge. The conceptual drawing on the right shows the hydrogeological setting resulting from this groundwater discharge shown on the left by the NVCA. The geologic layers are taken from the Ontario Geological Survey mapping for the Snow Valley Area. The blue arrows are a conceptual representation of groundwater flow. Their thickness is for illustrative purposes only. They have been drawn to show a gradual reduction in groundwater flow downward, as it moves through the geologic layers. The Golder (2016) report does not contain the water budget information necessary to allow estimates of the volumes of water which move between the various hydrogeological units.

24

Wetland Impacts

2017-03-08 25

Wetland Impacts

MRA text -Wells intercept groundwater before it reaches the Minesing Wetlands

2017-03-08 26

Proposed Sewage Discharge

27

A similar process happens with streams: pumping from a well can reduce the groundwater discharge to a stream. The colourful shapes show the capture zones for the new wells. From these, one can determine where stream flow reductions can be expected to occur. Because it maintains a constant temperature of about 10 degrees C , groundwater discharging into streams is considered “warm” in winter, thereby protecting trout eggs from freezing, and “cold” in summer, thereby preventing heat stress to fish. The treated sewage water to be discharged “downstream” cannot replace the natural groundwater to be removed from the streams “upstream” as a result of pumping. Sources: Golder (2016) Black and Veatch (2016) Well 16 capture zone: Map from Lake Simcoe SPA Approved Assessment Report F9-1

Summer / Winter Impact on Wildlife*

Groundwater removed by wells upstream lowers water levels in the creeks. Due to less water and the upstream removal of groundwater at a consistent 100C all year, water temperature will rise in summer and freeze in winter. Treated sewage water added downstream is warmer than groundwater, further raising the temperature. It will also change water quality and quantity. Will fish and other wildlife be adversely affected, even to the point of extinction?

2017-03-08 28

* Explanatory slide added by MRA

2017-03-08 29

GEOLOGIC MODEL + DRILLING PROGRAM

TH 22 TH 34 TH 21 Mathematical Model does not match soil samples extracted from test wells

30

In the above slide, the geological information obtained from drilling at 3 of the 4 proposed water supply locations is superimposed. A comparison of the test well results to the mathematical model shows that the field program contradicts the model.

2017-03-08 31

Ontario Geological Survey, 2011

32

The Ontario Geological Survey has studied the Midhurst area. The above drawing shows that the area has various layers, which can be divided into aquifers and aquitards. An interesting finding of the work of the Geological Survey is that sediments within the low lying areas reflect newer deposits, whereas deposits shown in the upland areas are essentially missing. The aquifers and aquitards of the upland areas may or may not be connected to the sediments within the valley fill areas (VFA) associated with the streams and wetlands.

Comparison of Geologic Models

2017-03-08 33

Ontario Geological Survey, 2011

Mathematical Model does not match 2011 Ontario Geological Survey

34

The above slide compares the Golder (2016) model cross-section to the Ontario Geological Survey conceptual geologic cross-section. The major difference is the way in which the model represents the valley fill areas (VFA) where sensitive surface water features are present. The Ontario Geological Survey layers do not extend through the VFAs because they are interpreted as having been eroded away during more recent geological events.

35

Proposed New Water Supply – Water Quality Treatment

Bubbles of gas = methane gas

36

• Disinfection
• Green sand filtration to lower

iron and manganese

• Ion exchange to lower elevated

nitrate

• Air stripping to remove volatile
• rganic compounds
• Note: current Midhurst wells

are disinfected and then sodium silicate added to keep iron in solution

Proposed New Water Supply – Water Quality Treatment

Conclusions

• 1. The predicted impacts are based on short-term pumping of individual wells.

Most of the aquifer tests described in the Golder (2016) study were for 3 days. It is not uncommon to conduct 30 day or longer tests to determine the nature of impacts in a multi-aquifer system such as is observed in the Midhurst area

• 2. Only some of the necessary 11 wells have been constructed
• 3. Combined pumping of all new wells at the required volume to meet the needs
• f the proposed development has not been done

4*. No water budget has been done.

2017-03-08 37

Conclusions

• 5. The hydrogeological study does not include a complete survey of private well use

and the potential for impacts to these private wells

• 6. An assessment of the possible limitations to land use within the new Well Head

Protection Areas has not been completed

• 7. The hydrogeological study does not include an assessment of stream flow

reductions along reaches of Willow and Matheson creek

8*. The hydrogeological study does not include an assessment of the impact on

fish and other wildlife

2017-03-08 38

Conclusions

• 9. The hydrogeological study does not include an assessment of the impact to the

Minesing Wetland complex 10*. Predictions of impacts from the proposed water-taking have been determined using an outdated mathematical groundwater model which differs from the actual field tests 11*. Cost of serving two different source water treatment plants will increase. 12*. Cost of treating “new” water will be much higher.

2017-03-08 39

* Added by MRA